U.S. patent application number 16/408433 was filed with the patent office on 2019-08-29 for viewing angle switchable display module.
This patent application is currently assigned to Coretronic Corporation. The applicant listed for this patent is Coretronic Corporation. Invention is credited to Ping-Yen Chen, Chung-Yang Fang, Yang-Ching Lin, Wen-Chun Wang, Jen-Wei Yu.
Application Number | 20190265522 16/408433 |
Document ID | / |
Family ID | 67684460 |
Filed Date | 2019-08-29 |
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United States Patent
Application |
20190265522 |
Kind Code |
A1 |
Chen; Ping-Yen ; et
al. |
August 29, 2019 |
VIEWING ANGLE SWITCHABLE DISPLAY MODULE
Abstract
A viewing angle switchable display module includes an organic
light-emitting display (OLED) panel, a viewing angle switchable
device disposed on the OLED panel, and a quarter wave plate
disposed between the OLED panel and the viewing angle switchable
device. The viewing angle switchable device includes an absorptive
polarizer, a reflective polarizer, and an electrically controlled
viewing angle switching element. A transmission axis of the
reflective polarizer is parallel to a transmission axis of the
absorptive polarizer. The electrically controlled viewing angle
switching element is disposed between the absorptive polarizer and
the reflective polarizer and includes two conductive layers and a
liquid crystal layer including liquid crystal molecules. When there
is a potential difference between the two conductive layers, an
orthogonal projection of an optical axis of each of the liquid
crystal molecules on the absorptive polarizer is parallel to or
perpendicular to the transmission axis of the absorptive
polarizer.
Inventors: |
Chen; Ping-Yen; (Hsin-Chu,
TW) ; Wang; Wen-Chun; (Hsin-Chu, TW) ; Fang;
Chung-Yang; (Hsin-Chu, TW) ; Lin; Yang-Ching;
(Hsin-Chu, TW) ; Yu; Jen-Wei; (Hsin-Chu,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Coretronic Corporation |
Hsin-Chu |
|
TW |
|
|
Assignee: |
Coretronic Corporation
Hsin-Chu
TW
|
Family ID: |
67684460 |
Appl. No.: |
16/408433 |
Filed: |
May 9, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16228777 |
Dec 21, 2018 |
|
|
|
16408433 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F 2201/44 20130101;
G02F 2413/05 20130101; G02F 1/13363 20130101; G02F 2413/01
20130101; G02F 1/1323 20130101; G02F 1/133536 20130101 |
International
Class: |
G02F 1/13 20060101
G02F001/13; G02F 1/13363 20060101 G02F001/13363; G02F 1/1335
20060101 G02F001/1335 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2017 |
CN |
201721843624.5 |
Claims
1. A viewing angle switchable display module, comprising: an
organic light-emitting display panel; a viewing angle switchable
device, disposed on a display surface of the organic light-emitting
display panel and comprising: an absorptive polarizer; a reflective
polarizer, disposed at a side of the absorptive polarizer, wherein
a transmission axis of the reflective polarizer is parallel to a
transmission axis of the absorptive polarizer; and an electrically
controlled viewing angle switching element, disposed between the
absorptive polarizer and the reflective polarizer and comprising
two conductive layers and a liquid crystal layer disposed between
the two conductive layers, wherein the liquid crystal layer
comprises a plurality of liquid crystal molecules, and when there
is a potential difference between the two conductive layers, an
orthogonal projection of an optical axis of each of the plurality
of liquid crystal molecules on the absorptive polarizer is parallel
to or perpendicular to the transmission axis of the absorptive
polarizer and the transmission axis of the reflective polarizer;
and a quarter wave plate, disposed between the organic
light-emitting display panel and the viewing angle switchable
device.
2. The viewing angle switchable display module as claimed in claim
1, wherein the viewing angle switchable device further comprises: a
compensation film, disposed between the absorptive polarizer and
the reflective polarizer and overlapped with the electrically
controlled viewing angle switching element.
3. The viewing angle switchable display module as claimed in claim
2, wherein the compensation film is an A-type plate, an O-type
plate, a C-type plate, a biaxial plate or a composite plate
constructed by at least two of the above four types of plates.
4. The viewing angle switchable display module as claimed in claim
2, wherein an out-of-plane retardation of the compensation film is
within a range from 200 nm to 700 nm.
5. The viewing angle switchable display module as claimed in claim
2, wherein an in-plane retardation of the compensation film is less
than 200 nm.
6. The viewing angle switchable display module as claimed in claim
2, further comprising: a compensation element, overlapped with the
organic light-emitting display panel and the viewing angle
switchable device, wherein the compensation element comprises a
compensation film and an absorptive polarizer, wherein a
transmission axis of the absorptive polarizer of the compensation
element is parallel to the transmission axis of the absorptive
polarizer and the transmission axis of the reflective
polarizer.
7. The viewing angle switchable display module as claimed in claim
6, wherein the compensation film of the compensation element is an
A-type plate, an O-type plate, a C-type plate, a biaxial plate or a
composite plate constructed by at least two of the above four types
of plates.
8. The viewing angle switchable display module as claimed in claim
1, further comprising: a compensation element, overlapped with the
organic light-emitting display pane and the viewing angle
switchable device, wherein the compensation element comprises a
compensation film and an absorptive polarizer, wherein a
transmission axis of the absorptive polarizer of the compensation
element is parallel to the transmission axis of the absorptive
polarizer and the transmission axis of the reflective
polarizer.
9. The viewing angle switchable display module as claimed in claim
8, wherein the compensation film of the compensation element is an
A-type plate, an O-type plate, a C-type plate or a composite plate
constructed by at least two of the above three types of plates.
10. The viewing angle switchable display module as claimed in claim
1, wherein the reflective polarizer has at least one opening, the
at least one opening is configured with another absorptive
polarizer, and a transmission axis of the another absorptive
polarizer is parallel to the transmission axis of the absorptive
polarizer and the transmission axis of the reflective
polarizer.
11. The viewing angle switchable display module as claimed in claim
1, wherein the reflective polarizer has at least one opening, and
the viewing angle switchable device further comprises another
absorptive polarizer, and wherein the reflective polarizer is
disposed between the another absorptive polarizer and the
electrically controlled viewing angle switching element, and a
transmission axis of the another absorptive polarizer is parallel
to the transmission axis of the absorptive polarizer and the
transmission axis of the reflective polarizer.
12. The viewing angle switchable display module as claimed in claim
1, further comprising: a polarized type viewing angle control
element, wherein the polarized type viewing angle control element
is located between the viewing angle switchable device and the
quarter wave plate, or the viewing angle switchable device is
located between the polarized type viewing angle control element
and the quarter wave plate.
13. The viewing angle switchable display module as claimed in claim
12, wherein the polarized type viewing angle control element
comprises: a biaxial compensation film; and a polarizer, wherein
the biaxial compensation film is located between the polarizer and
the viewing angle switchable device.
14. The viewing angle switchable display module as claimed in claim
13, wherein refractive indices of three principal axes of the
biaxial compensation film comprise Nx, Ny, and Nz, wherein Nz is
parallel to a thickness direction of the biaxial compensation film,
every two of Nx, Ny, and Nz are perpendicular to each other, an
angle between Nx and any one of the transmission axis of the
absorptive polarizer, the transmission axis of the reflective
polarizer, and a transmission axis of the polarizer is 45 degrees,
and an angle between Ny and any one of the transmission axis of the
absorptive polarizer, the transmission axis of the reflective
polarizer, and the transmission axis of the polarizer is 45
degrees.
15. The viewing angle switchable display module as claimed in claim
14, wherein Nx>Nz, and the transmission axis of the polarizer is
perpendicular to the transmission axis of the absorptive polarizer
and the transmission axis of the reflective polarizer.
16. The viewing angle switchable display module as claimed in claim
14, wherein Nz>Nx, and the transmission axis of the polarizer is
parallel to the transmission axis of the absorptive polarizer and
the transmission axis of the reflective polarizer.
17. The viewing angle switchable display module as claimed in claim
13, wherein the polarized type viewing angle control element
comprises a plurality of the biaxial compensation films and a
plurality of the polarizers, and the biaxial compensation films and
the polarizers are alternately arranged.
18. The viewing angle switchable display module as claimed in claim
13, wherein the polarized type viewing angle control element
further comprises an A-plate, a C-plate, or a combination of the
A-plate and the C-plate, the A-plate, the C-plate, or the
combination of the A-plate and the C-plate is located between the
viewing angle switchable device and the polarizer and overlaps the
biaxial compensation film.
19. The viewing angle switchable display module as claimed in claim
13, wherein an in-plane retardation of the polarized type viewing
angle control element is within a range from 200 nm to 300 nm, and
an out-of-plane retardation of the polarized type viewing angle
control element is within a range from 300 nm to 800 nm.
20. The viewing angle switchable display module as claimed in claim
12, wherein the polarized type viewing angle control element
comprises: a first O-plate compensation film, having a first
optical axis; a second O-plate compensation film, overlapped with
the first O-plate compensation film and having a second optical
axis; and a polarizer, wherein the first O-plate compensation film
and the second O-plate compensation film are located between the
polarizer and the viewing angle switchable device, a transmission
axis of the polarizer is parallel to the transmission axis of the
absorptive polarizer and the transmission axis of the reflective
polarizer, an orthogonal projection of the first optical axis on
the polarizer is parallel or perpendicular to the transmission axis
of the polarizer, the second optical axis and the first optical
axis have opposite inclination directions, and an orthogonal
projection of the second optical axis on the polarizer is parallel
or perpendicular to the transmission axis of the polarizer.
21. The viewing angle switchable display module as claimed in claim
20, wherein an acute angle included between the first optical axis
and the polarizer is in a range from 20.degree. to 50.degree., an
acute angle included between the second optical axis and the
polarizer is in a range from 20.degree. to 50.degree., and a
difference between the acute angle included between the first
optical axis and the polarizer and the acute angle included between
the second optical axis and the polarizer is no more than
5.degree..
22. The viewing angle switchable display module as claimed in claim
20, wherein a phase retardation value of the first O-plate
compensation film is in a range from 100 nm to 400 nm, a phase
retardation value of the second O-plate compensation film is in a
range from 100 nm to 400 nm, and a difference between the phase
retardation value of the first O-plate compensation film and the
phase retardation value of the second O-plate compensation film is
no more than 50 nm.
23. The viewing angle switchable display module as claimed in claim
20, wherein the polarized type viewing angle control element
further comprises: an adhesive layer, located between the first
O-plate compensation film and the second O-plate compensation
film.
24. The viewing angle switchable display module as claimed in claim
20, wherein the polarized type viewing angle control element
further comprises: a compensation film, located between the first
O-plate compensation film and the second O-plate compensation film,
between the first O-plate compensation film and the polarizer, or
between the second O-plate compensation film and the polarizer.
25. The viewing angle switchable display module as claimed in claim
24, wherein the compensation film is a C-plate compensation film or
an O-plate compensation film.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part application of
and claims the priority benefit of U.S. application Ser. No.
16/228,777, filed on Dec. 21, 2018, now pending, which claims the
priority benefit of China application serial no. 201721843624.5,
filed on Dec. 26, 2017. The entirety of the above-mentioned patent
application is hereby incorporated by reference herein and made a
part of this specification.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The invention relates to a display module, and particularly
relates to a viewing angle switchable display module.
Description of Related Art
[0003] Generally, a display device is usually designed to have a
wide viewing angle for displaying so as to be viewed by multiple
viewers. However, in some situations or on some occasions, for
example, when browsing a private website, viewing some confidential
information, or entering a password, a user may be subjected to
leak some private or confidential information due to the wide
viewing angle of a display which may be viewed by others somewhere
else. Generally, a light control film (LCF) may be placed in front
of a display to filter out wide-angled beams, so as to avoid a
peep. The light control film may be also removed manually for
displaying with a wide viewing angle. Since it is inconvenient for
a user to place or remove a LCF, a viewing angle switchable device
where the viewing angle of a display may be adjusted is in need.
With the viewing angle switchable device, a user may adjust or
select a wide-angle mode or a narrow-angle mode for the display as
required by operation.
[0004] The information disclosed in this "BACKGROUND OF THE
INVENTION" section is only for enhancement of understanding of the
background of the described technology and therefore it may contain
information that does not form the prior art that is already known
to a person of ordinary skill in the art. Further, the information
disclosed in the "BACKGROUND OF THE INVENTION" section does not
mean that one or more problems to be resolved by one or more
embodiments of the invention was acknowledged by a person of
ordinary skill in the art.
SUMMARY OF THE INVENTION
[0005] The invention provides a viewing angle switchable display
module, which may be switched between a general display mode and a
peep-avoiding mode by way of applying a voltage.
[0006] Other objects and advantages of the invention can be further
illustrated by the technical features broadly embodied and
described as follows.
[0007] In order to achieve one or a portion of or all of the
objects or other objects, an embodiment of the invention provides a
viewing angle switchable display module, including an organic
light-emitting display panel, a viewing angle switchable device,
and a quarter wave plate. The viewing angle switchable device is
disposed on a display surface of the organic light-emitting display
panel and includes an absorptive polarizer, a reflective polarizer,
and an electrically controlled viewing angle switching element. The
reflective polarizer is disposed at a side of the absorptive
polarizer, wherein a transmission axis of the reflective polarizer
is parallel to a transmission axis of the absorptive polarizer. The
electrically controlled viewing angle switching element is disposed
between the absorptive polarizer and the reflective polarizer and
includes two conductive layers and a liquid crystal layer disposed
between the two conductive layers, wherein the liquid crystal layer
includes a plurality of liquid crystal molecules. When there is a
potential difference between the two conductive layers, an
orthogonal projection of an optical axis of each of the plurality
of liquid crystal molecules on the absorptive polarizer is parallel
to or perpendicular to the transmission axis of the absorptive
polarizer and the transmission axis of the reflective polarizer.
The quarter wave plate is disposed between the organic
light-emitting display panel and the viewing angle switchable
device.
[0008] According to the above description, the embodiments of the
invention have at least one of the following advantages or effects.
In the embodiments of the invention, an inclination direction of
the liquid crystal molecules in the viewing angle switchable device
is controlled by changing a potential difference between the two
transparent conductive layers. A phase delay is caused in an
environmental light beam which enters the viewing angle switchable
device by a large angle, causing the environmental light beam to be
reflected by the reflective polarizer. A phase delay is caused in a
display light beam which enters the viewing angle switchable device
by a large angle may not pass through the absorptive polarizer
(i.e. may be absorbed by the absorptive polarizer). Since the
oblique environmental light beam is reflected by the reflective
polarizer and the oblique display light beam is absorbed by the
absorptive polarizer, a contrast of light leakage at large angle
(light leakage of the display light beam) is decreased, so as to
limit the range of the viewing angle (peep-avoiding). By way of
electrical control, a viewing angle switchable display module
employing the above-mentioned viewing angle switchable device may
be switched between a general display mode and a peep-avoiding
mode.
[0009] Other objectives, features and advantages of the present
invention will be further understood from the further technological
features disclosed by the embodiments of the present invention
wherein there are shown and described preferred embodiments of this
invention, simply by way of illustration of modes best suited to
carry out the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of this specification. The drawings illustrate
embodiments of the invention and, together with the description,
serve to explain the principles of the invention. The drawings are
not necessarily drawn to scale.
[0011] FIG. 1 is a cross-sectional view schematically illustrating
a viewing angle switchable device in a general display mode
according to a first embodiment of the invention.
[0012] FIG. 2, FIG. 3, FIG. 4A and FIG. 5 are respectively
cross-sectional views schematically illustrating viewing angle
switchable devices in the general display mode according to a
second embodiment to a fifth embodiment of the invention.
[0013] FIG. 4B is a top view schematically illustrating a
reflective polarizer in FIG. 4A.
[0014] FIG. 6A and FIG. 6B are cross-sectional views respectively
in an X-Z reference plane and a Y-Z reference plane schematically
illustrating a viewing angle switchable display module in the
general display mode according to a first embodiment of the
invention. FIG. 6A and FIG. 6B respectively illustrate travelling
paths of a display light beam with respect to the X-Z reference
plane and the Y-Z reference plane.
[0015] FIG. 6C is a schematic diagram of angle distribution, which
represents transmittances at different viewing angles of the
viewing angle switchable display module in the general display mode
of the first embodiment.
[0016] FIG. 7A and FIG. 7B are cross-sectional views respectively
in the X-Z reference plane and the Y-Z reference plane
schematically illustrating a viewing angle switchable display
module in an peep-avoiding mode in according to the first
embodiment of the invention. FIG. 7A and FIG. 7B respectively
illustrate travelling paths of the display light beam with respect
to the X-Z reference plane and the Y-Z reference plane.
[0017] FIG. 7C is a cross-sectional view of a viewing angle
switchable display module in the peep-avoiding mode in the Y-Z
reference plane according to the first embodiment of the invention,
and FIG. 7C illustrates a travelling path of an environmental light
beam on the Y-Z reference plane.
[0018] FIG. 7D is a schematic diagram of angle distribution, which
represents transmittances at different viewing angles of the
viewing angle switchable display module in the peep-avoiding mode
of the first embodiment.
[0019] FIG. 8 and FIG. 9 are cross-sectional views schematically
illustrating viewing angle switchable display modules according to
a second embodiment and a third embodiment of the invention.
[0020] FIG. 10A and FIG. 10B are cross-sectional views respectively
in the X-Z reference plane and the Y-Z reference plane
schematically illustrating a viewing angle switchable display
module in the general display mode according to a fourth embodiment
of the invention. FIG. 10A and FIG. 10B respectively illustrate
travelling paths of environmental light beams with respect to the
X-Z reference plane and the Y-Z reference plane.
[0021] FIG. 10C is a cross-sectional view of the viewing angle
switchable display module in the peep-avoiding mode in the Y-Z
reference plane according to the fourth embodiment of the
invention, and FIG. 10C illustrates travelling paths of
environmental light beams on the Y-Z reference plane.
[0022] FIG. 10D and FIG. 10E are other cross-sectional views
schematically illustrating viewing angle switchable display modules
according to the fourth embodiment of the invention.
[0023] FIG. 11 to FIG. 18 are cross-sectional views schematically
illustrating viewing angle switchable display modules according to
a fifth embodiment to a twelfth embodiment of the invention.
DESCRIPTION OF EMBODIMENTS
[0024] In the following detailed description of the preferred
embodiments, reference is made to the accompanying drawings which
form a part hereof, and in which are shown by way of illustration
specific embodiments in which the invention may be practiced. In
this regard, directional terminology, such as "top," "bottom,"
"front," "back," etc., is used with reference to the orientation of
the Figure(s) being described. The components of the present
invention can be positioned in a number of different orientations.
As such, the directional terminology is used for purposes of
illustration and is in no way limiting. On the other hand, the
drawings are only schematic and the sizes of components may be
exaggerated for clarity. It is to be understood that other
embodiments may be utilized and structural changes may be made
without departing from the scope of the present invention. Also, it
is to be understood that the phraseology and terminology used
herein are for the purpose of description and should not be
regarded as limiting. The use of "including," "comprising," or
"having" and variations thereof herein is meant to encompass the
items listed thereafter and equivalents thereof as well as
additional items. Unless limited otherwise, the terms "connected,"
"coupled," and "mounted" and variations thereof herein are used
broadly and encompass direct and indirect connections, couplings,
and mountings. Similarly, the terms "facing," "faces" and
variations thereof herein are used broadly and encompass direct and
indirect facing, and "adjacent to" and variations thereof herein
are used broadly and encompass directly and indirectly "adjacent
to". Therefore, the description of "A" component facing "B"
component herein may contain the situations that "A" component
directly faces "B" component or one or more additional components
are between "A" component and "B" component. Also, the description
of "A" component "adjacent to" "B" component herein may contain the
situations that "A" component is directly "adjacent to" "B"
component or one or more additional components are between "A"
component and "B" component. Accordingly, the drawings and
descriptions will be regarded as illustrative in nature and not as
restrictive.
[0025] FIG. 1 is a cross-sectional view schematically illustrating
a viewing angle switchable device in a general display mode
according to a first embodiment of the invention. Referring to FIG.
1, a viewing angle switchable device 100 of the first embodiment of
the invention includes an absorptive polarizer 110, a reflective
polarizer 120 and an electrically controlled viewing angle
switching element 130.
[0026] The reflective polarizer 120 is disposed at a side of the
absorptive polarizer 110, and a transmission axis T120 of the
reflective polarizer 120 is parallel to a transmission axis T110 of
the absorptive polarizer 110. The electrically controlled viewing
angle switching element 130 is disposed between the absorptive
polarizer 110 and the reflective polarizer 120, and the
electrically controlled viewing angle switching element 130
includes a transparent substrate SUB1, a transparent substrate
SUB2, a transparent conductive layer TC1, a transparent conductive
layer TC2, and a liquid crystal layer LC.
[0027] The transparent substrate SUB1 and the transparent substrate
SUB2 are disposed opposite to each other. The transparent
conductive layer TC1 and the transparent conductive layer TC2 are
disposed between the transparent substrate SUB1 and the transparent
substrate SUB2. The liquid crystal layer LC is disposed between the
transparent conductive layer TC1 and the transparent conductive
layer TC2, and the liquid crystal layer LC includes a plurality of
liquid crystal molecules LCM. In the embodiment, the electrically
controlled viewing angle switching element 130 may further include
an alignment layer AL1 and an alignment layer AL2, where the
alignment layer AL1 is disposed between the transparent conductive
layer TC1 and the liquid crystal layer LC, and the alignment layer
AL2 is disposed between the transparent conductive layer TC2 and
the liquid crystal layer LC, so as to orient the liquid crystal
molecules LCM.
[0028] When there is no potential difference between the
transparent conductive layer TC1 and the transparent conductive
layer TC2, an optical axis OA of each of the liquid crystal
molecules LCM may be substantially parallel to or perpendicular to
the absorptive polarizer 110 and the reflective polarizer 120
through the alignment layer AL1 and the alignment layer AL2. In
other words, an orthogonal projection POA of the optical axis OA of
each of the liquid crystal molecules LCM on the absorptive
polarizer 110 is substantially parallel to or perpendicular to the
transmission axis T110 of the absorptive polarizer 110 and the
transmission axis T120 of the reflective polarizer 120. On the
other hand, when there is a potential difference between the
transparent conductive layer TC1 and the transparent conductive
layer TC2, the liquid crystal molecules LCM are tilted (not shown
in FIG. 1) due to the potential difference, and the orthogonal
projection POA of the optical axis OA of each of the liquid crystal
molecules LCM on the absorptive polarizer 110 is parallel to or
perpendicular to the transmission axis T110 of the absorptive
polarizer 110 and the transmission axis T120 of the reflective
polarizer 120.
[0029] Further, as shown in FIG. 1, with the transmission axis T110
of the absorptive polarizer 110 and the transmission axis T120 of
the reflective polarizer 120 both extending in a first direction X,
the alignment layer AL1 and the alignment layer AL2 may be both
oriented in a horizontal alignment in parallel to the first
direction X (or a second direction Y), such that when there is no
potential difference between the transparent conductive layer TC1
and the transparent conductive layer TC2, the optical axis OA of
each of the liquid crystal molecules LCM substantially extends
along the first direction X (or the second direction Y).
Alternatively, the alignment layer AL1 and the alignment layer AL2
may be both oriented in a vertical alignment, i.e. when there is no
potential difference between the transparent conductive layer TC1
and the transparent conductive layer TC2, the optical axis OA of
each of the liquid crystal molecules LCM substantially extends
along a direction Z of the thickness of the viewing angle
switchable device 100 (not shown in FIG. 1). Regardless of the
horizontal alignment or the vertical alignment, when there is a
potential difference between the transparent conductive layer TC1
and the transparent conductive layer TC2, the liquid crystal
molecules LCM are tilted due to the potential difference, such that
the optical axis OA of each of the liquid crystal molecules LCM is
inclined (not shown in FIG. 1) relative to the transmission axis
T110 of the absorptive polarizer 110 and the transmission axis T120
of the reflective polarizer 120, i.e. an angle ranging from 0 to 90
is formed between the optical axis OA of each of the liquid crystal
molecules LCM and the transmission axis T110 of the absorptive
polarizer 110 (or between the optical axis OA of each of the liquid
crystal molecules LCM and the transmission axis T120 of the
reflective polarizer 120). Moreover, when there is a potential
difference between the transparent conductive layer TC1 and the
transparent conductive layer TC2, the orthogonal projection POA of
the optical axis OA of each of the liquid crystal molecules LCM on
the absorptive polarizer 110 (or on the reflective polarizer 120)
is parallel to or perpendicular to the transmission axis T110 of
the absorptive polarizer 110 and the transmission axis T120 of the
reflective polarizer 120. To be specific, the orthogonal projection
POA of the optical axis OA of each of the liquid crystal molecules
LCM on the absorptive polarizer 110 (or on the reflective polarizer
120) extends along the first direction X or the second direction
Y.
[0030] By changing the potential difference between the transparent
conductive layer TC1 and the transparent conductive layer TC2, an
inclination direction of the liquid crystal molecules LCM is
controlled. As such, a phase delay is caused in a light beam which
enters the viewing angle switchable device 100 by a large angle
along the second direction Y, such that the light beam cannot pass
through the absorptive polarizer 110. As a result, the range of the
viewing angle is narrowed (peep-avoiding). As for a viewing angle
switchable display module employing the viewing angle switchable
device 100, it may be switched between a general display mode and a
peep-avoiding mode in an electric control manner (as described in
further detail from FIG. 6A to FIG. 7D). Besides the peep-avoiding,
with the configuration of the reflective polarizer 120, an
environmental light beam which enters the viewing angle switchable
device 100 by a large angle is reflected by the reflective
polarizer 120, so as to enhance the reflection of the environmental
light beam by the viewing angle switchable device 100. As such, a
contrast of large angle light leakage of the viewing angle
switchable device 100 is decreased so as to help avoid a peep from
a large angle.
[0031] Other implementations of the viewing angle switchable device
are described below with reference of FIG. 2 to FIG. 5, where the
same components are denoted by the same referential numbers, and
details thereof are not repeated. FIG. 2, FIG. 3, FIG. 4A and FIG.
5 are respectively cross-sectional views schematically illustrating
viewing angle switchable devices in the general display mode
according to a second embodiment to a fifth embodiment of the
invention. FIG. 4B is a top view schematically illustrating a
reflective polarizer in FIG. 4A.
[0032] Referring to FIG. 2, main differences between the viewing
angle switchable device 200 of the second embodiment of the
invention and the viewing angle switchable device 100 of FIG. 1 are
as follows. The viewing angle switchable device 200 further
includes a compensation film 140. The compensation film 140 is
disposed between the absorptive polarizer 110 and the reflective
polarizer 120 and is overlapped with the electrically controlled
viewing angle switching element 130. As shown in FIG. 2, the
compensation film 140 may be located between the electrically
controlled viewing angle switching element 130 and the reflective
polarizer 120, though the invention is not limited thereto. In
another embodiment, the compensation film 140 may be located
between the electrically controlled viewing angle switching element
130 and the absorptive polarizer 110.
[0033] The compensation film 140 may be an A-type plate, an O-type
plate, a C-type (e.g. negative C-type) plate, a biaxial plate or a
composite plate constructed by at least two of the above four types
of plates. Each of the A-type plate, the O-type plate and the
C-type (e.g. negative C-type) plate may be made of liquid crystal
polymers. As for the A-type plate, optical axes of the liquid
crystal polymers are parallel to a film surface of the A-type
plate. As for the O-type plate, optical axes of the liquid crystal
polymers are inclined relative to a film surface of the O-type
plate. As for the C-type (e.g. negative C-type) plate, optical axes
of the liquid crystal polymers are perpendicular to a film surface
of the C-type e.g. negative C-type) plate. Moreover, an
out-of-plane retardation (also referred to as "Rth") of the
compensation film 140 may be within a range from 200 nm to 700 nm.
And an in-plane retardation (also referred to as "Ro") of the
compensation film 140 may be less than 200 nm. The out-of-plane
retardation of the compensation film 140 equals to
[(Nx+Ny)/2-Nz]*D, wherein Nx, Ny, and Nz are refractive indices of
three principal axes of the compensation film 140, and D is the
thickness of the compensation film 140. The in-plane retardation of
the biaxial compensation film 140 equals to (Nx-Ny)*D. Every two of
Nx, Ny, and Nz are perpendicular to each other, wherein Nz is
parallel to the thickness direction of the compensation film 140,
and Nx and Ny, are parallel to the compensation film 140.
[0034] By configuring the compensation film 140, the large angle
light leakage of the viewing angle switchable device 200 in the
second direction Y is mitigated. Besides, the large angle light
leakage in an azimuth 0.+-.45 degrees and an azimuth 180.+-.45
degrees is decreased, and reflection of the environmental light
beam in the azimuth 0.+-.45 degrees and the azimuth 180.+-.45
degrees is increased, so as to decrease the contrast of the oblique
viewing angle. As such, peep from a large angle is avoided. As for
a viewing angle switchable display module employing the viewing
angle switchable device 200, in the general display mode, the
viewing angle of a display image is not limited by the electrically
controlled viewing angle switching element 130 and the compensation
film 140 disposed between the absorptive polarizer 110 and the
reflective polarizer 120. On the other hand, in the peep-avoiding
mode, a phase delay is caused in the light beam entering the
viewing angle switchable device 200 by a large angle and passing
through the electrically controlled viewing angle switching element
130 via the electric control manner, and the large angle light
leakage of the azimuth 0.+-.45 degrees and the azimuth 180.+-.45
degrees is decreased by using the compensation film 140. As such, a
peep from a large angle is effectively avoided. Moreover, in the
embodiment, the reflection of the environmental light beam is
enhanced by using the reflective polarizer 120, thus the contrast
of the large angle light leakage is decreased and a peep from a
large angle is effectively avoided.
[0035] Referring to FIG. 3, main differences between the viewing
angle switchable device 300 of the third embodiment of the
invention and the viewing angle switchable device 100 of FIG. 1 are
as follows. The viewing angle switchable device 300 further
includes a compensation element 150. The compensation element 150
includes a compensation film 152 and an absorptive polarizer 154.
The compensation film 152 of the compensation element 150 may be an
A-type plate, an O-type plate, a C-type (e.g. negative C-type)
plate, a biaxial plate or a composite plate constructed by at least
two of the above four types of plates. Moreover, a transmission
axis T154 of the absorptive polarizer 154 of the compensation
element 150 is parallel to the transmission axis T110 of the
absorptive polarizer 110 and the transmission axis T120 of the
reflective polarizer 120.
[0036] The compensation element 150 may be disposed adjacent to the
absorptive polarizer 110 or adjacent to the reflective polarizer
120, and the compensation film 152 of the compensation element 150
is disposed between the absorptive polarizer 154 of the
compensation element 150 and an adjacent polarizer (the absorptive
polarizer 110 or the reflective polarizer 120). In the embodiment,
the compensation element 150 is disposed on a surface 5120 of the
reflective polarizer 120 away from the electrically controlled
viewing angle switching element 130, and the compensation film 152
of the compensation element 150 is disposed between the absorptive
polarizer 154 of the compensation element 150 and the reflective
polarizer 120. For example, the absorptive polarizer 154 of the
compensation element 150 is disposed on a surface of the
compensation film 152 of the compensation element 150 away from the
electrically controlled viewing angle switching element 130 (for
example, a lower surface S152B of the compensation film 152),
though the invention is not limited thereto. In another embodiment,
the compensation element 150 may be disposed on a surface 5110 of
the absorptive polarizer 110 away from the electrically controlled
viewing angle switching element 130, and the compensation film 152
of the compensation element 150 is disposed between the absorptive
polarizer 154 of the compensation element 150 and the absorptive
polarizer 110. For example, the absorptive polarizer 154 of the
compensation element 150 is disposed on a surface of the
compensation film 152 of the compensation element 150 away from the
electrically controlled viewing angle switching element 130.
[0037] By configuring the compensation element 150, the large angle
light leakage of the viewing angle switchable device 300 in the
second direction Y is mitigated. Besides, the large angle light
leakage of the azimuth 0.+-.45 degrees and the azimuth 180.+-.45
degrees is also decreased, such that a better peep-avoiding effect
is achieved. As for a viewing angle switchable display module
employing the viewing angle switchable device 300, in the
peep-avoiding mode, a phase delay is caused in the light beam
entering the viewing angle switchable device 300 by a large angle
and passing through the electrically controlled viewing angle
switching element 130 via the electric control manner, and the
large angle light leakage of the azimuth 0.+-.45 degrees and the
azimuth 180.+-.45 degrees is decreased by using the compensation
component 150. As such, a peep from a large angle is effectively
avoided.
[0038] In an embodiment, the viewing angle switchable device 300
may further include the compensation film 140 of FIG. 2.
[0039] Referring to FIG. 4A and FIG. 4B, main differences between
the viewing angle switchable device 400 of the fourth embodiment of
the invention and the viewing angle switchable device 100 of FIG. 1
are as follows. In the viewing angle switchable device 400, the
reflective polarizer 120A has at least one opening O. In FIG. 4B,
the reflective polarizer 120A has 5 openings O, and each of the
openings O is a quadrilateral opening. However, the number and the
shape of the openings O and the distribution of the openings O in
the reflective polarizer 120A may be changed as required, which are
not limited to the embodiments shown in FIG. 4A and FIG. 4B.
Moreover, each of the openings O may be configured with another
absorptive polarizer (for example, an absorptive polarizer 160),
and a transmission axis T160 of the absorptive polarizer 160 is
parallel to the transmission axis T110 of the absorptive polarizer
110 and the transmission axis T120 of the reflective polarizer
120.
[0040] The reflective polarizer 120A has a predetermined pattern
through the openings O of the reflective polarizer 120A. Since the
predetermined pattern is reflected when an environmental light beam
enters the viewing angle switchable device 300 by a large angle,
the large angle light leakage is interfered. As such, the openings
O of the reflective polarizer 120A are favourable in
peep-avoiding.
[0041] In an embodiment, the viewing angle switchable device 400
may further include the compensation film 140 of FIG. 2, the
compensation element 150 of FIG. 3, or a combination of the
compensation film 140 of FIG. 2 and the compensation element 150 of
FIG. 3.
[0042] Referring to FIG. 5, main differences between the viewing
angle switchable device 500 of the fifth embodiment of the
invention and the viewing angle switchable device 400 of FIG. 4A
are as follows. In the viewing angle switchable device 400, each
opening O is configured with one absorptive polarizer 160. Namely,
the number of the absorptive polarizers 160 and the number of the
openings O are identical. In the viewing angle switchable device
500, the reflective polarizer 120A is disposed between the
absorptive polarizer 160 and the electrically controlled viewing
angle switching element 130, and the number of the absorptive
polarizer 160 is one. Moreover, the absorptive polarizer 160 covers
all of the openings O.
[0043] In an embodiment, the viewing angle switchable device 500
may further include the compensation film 140 of FIG. 2, the
compensation element 150 of FIG. 3, or a combination of the
compensation film 140 of FIG. 2 and the compensation element 150 of
FIG. 3.
[0044] The general display mode and the peep-avoiding mode of a
viewing angle switchable display module employing the viewing angle
switchable devices of the invention are described below with
reference of FIG. 6A to FIG. 7D. FIG. 6A and FIG. 6B are
cross-sectional views respectively in an X-Z reference plane and a
Y-Z reference plane schematically illustrating a viewing angle
switchable display module in the general display mode according to
a first embodiment of the invention. FIG. 6A and FIG. 6B
respectively illustrate travelling paths of a display light beam
with respect to the X-Z reference plane and the Y-Z reference
plane. FIG. 6C is a schematic diagram of angle distribution, which
represents transmittances at different viewing angles of the
viewing angle switchable display module in the general display mode
of the first embodiment. FIG. 7A and FIG. 7B are cross-sectional
views respectively in the X-Z reference plane and the Y-Z reference
plane schematically illustrating a viewing angle switchable display
module in an peep-avoiding mode in according to the first
embodiment of the invention. FIG. 7A and FIG. 7B respectively
illustrate travelling paths of the display light beam with respect
to the X-Z reference plane and the Y-Z reference plane. FIG. 7C is
a cross-sectional view of a viewing angle switchable display module
in the peep-avoiding mode in the Y-Z reference plane according to
the first embodiment of the invention, and FIG. 7C illustrates a
travelling path of an environmental light beam on the Y-Z reference
plane. FIG. 7D is a schematic diagram of angle distribution, which
represents transmittances at different viewing angles of the
viewing angle switchable display module in the peep-avoiding mode
of the first embodiment.
[0045] Referring to FIG. 6A and FIG. 6B, a viewing angle switchable
display module 10 of the first embodiment of the invention includes
a display panel DP and a viewing angle switchable device (for
example, the viewing angle switchable device 100 of FIG. 1).
[0046] The display panel DP may be any type of display panel, for
example, a self-luminous display panel or a non-self-luminous
display panel. The self-luminous display panel is, for example, an
organic light-emitting display panel. On the other hand, the
non-self-luminous display panel is, for example, a liquid crystal
display panel, though the invention is not limited thereto. When
the display panel DP is the non-self-luminous display panel, the
display module 10 may include a polarizer or further include a
backlight module (not shown). The backlight module may be a direct
type backlight module or a side incident type backlight module.
When the display panel DP is the self-luminous display panel, the
display module 10 may or may not include a polarizer and do not
further include a backlight module (not shown).
[0047] The display module DP may have one polarizer (for example,
an absorptive polarizer). Further, the display panel DP may have a
polarizer P located at a light emitting side of the display panel
DP, so as to output light beams with a specific polarization
direction. Moreover, a transmission axis TDP of the polarizer P is
parallel to the transmission axis T120 of the reflective polarizer
120, such that the light beam passing through the polarizer P may
further pass through the reflective polarizer 120. In the
embodiment, the transmission axis TDP of the polarizer P is
parallel to the first direction X and an opposite direction of the
first direction X, so that the polarizer P allows the display light
beam with a polarization direction (for example, a first
polarization direction P1) parallel to the first direction X and
the opposite direction of the first direction X to pass through,
and blocks the display light beam with a polarization direction
(for example, a second polarization direction P2) parallel to the
second direction Y and an opposite direction of the second
direction Y. In another embodiment, the display panel DP may
further has another polarizer (not shown), and the another
polarizer is located at a light incident side of the display panel
DP, where a transmission axis of the polarizer located at the light
incident side of the display panel DP may be parallel to or
perpendicular to the transmission axis TDP of the polarizer P.
[0048] The viewing angle switchable device 100 is disposed on a
display surface S (for example, a light emitting surface of the
polarizer P) of the display panel DP and is switched between the
general display mode and the peep-avoiding mode in an electric
control manner, which is described in detail below.
[0049] Referring to FIG. 6A to FIG. 6C, when there is no potential
difference between the transparent conductive layer TC1 and the
transparent conductive layer TC2, a polarization direction of the
display light beam entering the viewing angle switchable device 100
from the reflective polarizer 120 is parallel to an orthogonal
projection of the optical axis OA of each of the liquid crystal
molecules LCM on a polarization plane (a plane perpendicular to a
travelling path of the display light beam). As such, transmittances
of the display light beams at various incident angles (including a
display light beam B1 vertically entering the viewing angle
switchable device 100 and a display light beam B2 entering the
viewing angle switchable device 100 by a large angle) is not
influenced. Moreover, since a reflectivity of the display panel DP
is very low, when the environmental light beam is incident to the
viewing angle switchable device 100, both the environmental light
beam vertically entering the viewing angle switchable device 100
and the environmental light beam entering the viewing angle
switchable device 100 by a large angle are absorbed by the display
panel DP. As a result, in a general display mode, the display image
is prevented from being interfered by the environmental light
beam.
[0050] Referring to FIG. 7A to FIG. 7D, when there is a potential
difference between the transparent conductive layer TC1 and the
transparent conductive layer TC2, the optical axis OA of each of
the liquid crystal molecules LCM is tilted due to an electric
field. In FIG. 7A to FIG. 7D, the orthogonal projection POA of the
optical axis OA of each of the liquid crystal molecules LCM on the
absorptive polarizer 110 extends in the first direction X, i.e.
when there is a potential difference between the transparent
conductive layer TC1 and the transparent conductive layer TC2, the
orthogonal projection POA of the optical axis OA of each of the
liquid crystal molecules LCM on the absorptive polarizer 110 is
parallel to the transmission axis T110 of the absorptive polarizer
110 and the transmission axis T120 of the reflective polarizer 120,
though the invention is not limited thereto. In another embodiment,
the orthogonal projection POA of the optical axis OA of each of the
liquid crystal molecules LCM on the absorptive polarizer 110 may
extend in a second direction Y, i.e. when there is a potential
difference between the transparent conductive layer TC1 and the
transparent conductive layer TC2, the orthogonal projection POA of
the optical axis OA of each of the liquid crystal molecules LCM on
the absorptive polarizer 110 may be perpendicular to the
transmission axis T110 of the absorptive polarizer 110 and the
transmission axis T120 of the reflective polarizer 120.
[0051] Referring to FIG. 7A, as for the display light beam on the
X-Z reference plane, a polarization direction of the display light
beam is also parallel to the orthogonal projection of the optical
axis OA of each of the liquid crystal molecules LCM on the
polarization plane, so that transmittances of the display light
beams at various incident angles (including the display light beam
B1 vertically entering the viewing angle switchable device 100 and
the display light beam B2 entering the viewing angle switchable
device 100 by a large angle) is not influenced. Referring to FIG.
7B, as for the display light beam on the Y-Z reference plane, a
polarization direction of the display light beam B1 vertically
entering the viewing angle switchable device 100 is also parallel
to the orthogonal projection of the optical axis OA of each of the
liquid crystal molecules LCM on the polarization plane, so that the
transmittances of the display light beam B1 vertically entering the
viewing angle switchable device 100 is not influenced. However, the
polarization direction of the display light beam B2 incident to the
viewing angle switchable device 100 by a large angle and the
orthogonal projection of the optical axis OA of each of the liquid
crystal molecules LCM on the polarization plane form an angle
therebetween, such that the polarization direction of the display
light beam B2 is changed. The larger the angle is, the less of
display light beam B2 passing through the absorptive polarizer 110
(i.e. the transmittance is lower). As a result, a peep is avoiding
by narrowing the range of the viewing angle from the second
direction Y and the opposite direction of the second direction
Y.
[0052] Referring to FIG. 7C, it should be noted that, as for the
environmental light beam on the Y-Z reference plane, a polarization
direction of the environmental light beam B3 vertically entering
the viewing angle switchable device 100 is parallel to the
orthogonal projection of the optical axis OA of each of the liquid
crystal molecules LCM on the polarization plane, so that in the
peep-avoiding mode, the environmental light beam B3 vertically
entering the viewing angle switchable device 100 is absorbed by the
display panel DP without the display image from a front view. On
the other hand, a polarization direction of an environmental light
beam B4 incident to the viewing angle switchable device 100 by a
large angle and the orthogonal projection of the optical axis OA of
each of the liquid crystal molecules LCM on the polarization plane
form an angle therebetween, such that the polarization direction of
the environmental light beam B4 is changed. Subsequently, a part of
the environmental light beam B4 is reflected by the reflective
polarizer 120. The environmental light beam B4 reflected by the
reflective polarizer 120 may again pass through the liquid crystal
layer LC to change the polarization direction of the environmental
light beam B4. Then, the environmental light beam B4 may pass
through the absorptive polarizer 110. Since the environmental light
beam B4 is reflected by the reflective polarizer 120 and then
passes through the absorptive polarizer 110, reflection of the
environmental light beam by the viewing angle switchable device 100
is enhanced. By enhancing the reflection of the environmental light
beam, the contrast of the large angle light leakage is decreased,
and thus a peep is further avoided.
[0053] In another embodiment, the viewing angle switchable device
100 of the viewing angle switchable display module 10 may be
replaced by the viewing angle switchable device 200 of FIG. 2, the
viewing angle switchable device 300 of FIG. 3, the viewing angle
switchable device 400 of FIG. 4A, or the viewing angle switchable
device 500 of FIG. 5. In still another embodiment, the viewing
angle switchable display module 10 may adopt the viewing angle
switchable device 100 of FIG. 1 (or the viewing angle switchable
device 200 of FIG. 2, the viewing angle switchable device 400 of
FIG. 4A, or the viewing angle switchable device 500 of FIG. 5), and
the viewing angle switchable display module 10 may further include
the compensation element 150 of FIG. 3, where the compensation
element 150, the display panel DP and the viewing angle switchable
device 100 are overlapped with each other. For example, the
compensation element 150 and the viewing angle switchable device
100 may be sequentially disposed on the display panel DP, or
positions of the compensation element 150 and the viewing angle
switchable device 100 may be exchanged.
[0054] Other implementations of the viewing angle switchable
display module 10 are described below with reference of FIG. 8 and
FIG. 9, where the same components are denoted by the same
referential numbers, and details thereof are not repeated. FIG. 8
and FIG. 9 are cross-sectional views schematically illustrating
viewing angle switchable display modules according to a second
embodiment and a third embodiment of the invention.
[0055] Referring to FIG. 8, main differences between the viewing
angle switchable display module 20 of the second embodiment of the
invention and the viewing angle switchable display module 10 of
FIG. 6A are as follows. In the viewing angle switchable display
module 10 of FIG. 6A, the display panel DP may be a self-luminous
display panel, such as an organic light-emitting display panel. In
the viewing angle switchable display module 20, the display panel
DP is a non-self-luminous display panel, such as an
In-Plane-Switching (IPS) liquid crystal display panel, though the
invention is not limited thereto. Moreover, the viewing angle
switchable display module 20 further includes a collimation
backlight module BL, an electrically controlled optical diffuser
ED, and the compensation element 150 of FIG. 3.
[0056] The collimation backlight module BL may be implemented by
any conventionally backlight module which may provide a collimated
light beam. The electrically controlled optical diffuser ED may
include two transparent substrates (not shown), two transparent
conductive layers (not shown) disposed between the two transparent
substrates and a Polymer-Dispersed Liquid Crystal (PDLC) (not
shown) disposed between the two transparent conductive layers. When
there is no potential difference between the two transparent
conductive layers, the PDLC may be in a transparent state, and when
there is a potential difference between the two transparent
conductive layers, the PDLC may be in a scattering state. In the
general display mode, the PDLC in the scattering state may provide
a planar light source with a more uniform light intensity
distribution. In the peep-avoiding mode, the PDLC in the
transparent state may provide a collimated planar light source.
[0057] Besides the polarizer P, the display panel DPA further
includes a polarizer PA, and the polarizer PA is located at a light
incident side (a side of the display panel DPA facing the
collimation backlight module BL) of the display panel DPA. In the
embodiment, the display panel DPA is located between the viewing
angle switchable device 100 and the compensation element 150. The
transmission axis TDP of the polarizer P is perpendicular to a
transmission axis TDPA of the polarizer PA. Moreover, the
transmission axis TDP of the polarizer P, the transmission axis
T120 of the reflective polarizer 120 and the transmission axis T110
of the absorptive polarizer 110 are parallel to each other, and the
orthogonal projection POA of the optical axis OA of each of the
liquid crystal molecules LCM in the viewing angle switchable device
100 on the absorptive polarizer 110 is parallel to or perpendicular
to the transmission axis T110 of the absorptive polarizer 110,
while the transmission axis TDPA of the polarizer PA is parallel to
the transmission axis T154 of the absorptive polarizer 154 of the
compensation element 150. However, the relative configuration
relationships of the above components and the extending directions
of the transmission axes may be changed as required, which are not
limited to the implementation shown in FIG. 8.
[0058] For example, in another embodiment, the compensation element
150 may be located between the viewing angle switchable device 100
and the display panel DPA. In still another embodiment, the
compensation element 150 may be omitted in the configuration of
FIG. 8, and the compensation film 152 is disposed between the
polarizer P and the reflective polarizer 120. In yet another
embodiment, the compensation element 150 is omitted. In any of the
aforementioned embodiments, the viewing angle switchable device 100
may be replaced by the viewing angle switchable device 200 of FIG.
2, the viewing angle switchable device 400 of FIG. 4A or the
viewing angle switchable device 500 of FIG. 5.
[0059] Referring to FIG. 9, main differences between the viewing
angle switchable display module 30 of the third embodiment of the
invention and the viewing angle switchable display module 20 of
FIG. 8 are as follows. The compensation element 150 and the
electrically controlled optical diffuser ED of FIG. 8 are omitted
from the viewing angle switchable display module 30. Moreover, the
collimation backlight module BL is replaced by a backlight module
BLA. The backlight module BLA includes at least one diffuser F1, a
prism sheet F2 and a prism sheet F3. In the embodiment, the
backlight module BLA may further include at least one
light-emitting element LE, a light guide plate LGP and a reflector
R. The light guide plate LGP has a light entering surface SI, a
bottom surface SB and a light emitting surface SE, where the bottom
surface SB and the light emitting surface SE are opposite to each
other, and the light entering surface SI is connected to the bottom
surface SB and the light emitting surface SE. The light-emitting
element LE is disposed beside the light entering surface SI. The
reflector R is located below the bottom surface SB. The diffuser
F1, the prism sheet F2 and the prism sheet F3 are sequentially
stacked on the light emitting surface SE.
[0060] In another embodiment, the backlight module BLA may further
include another diffuser or a Dual Brightness Enhancement Film
(DBEF), and this another diffuser (or the DBEF) may be disposed on
the prism sheet F3. Moreover, the viewing angle switchable display
module 20 may further include the compensation element 150 of FIG.
8, and the compensation element 150 may be disposed between the
backlight module BLA and the display panel DPA or between the
viewing angle switchable device 100 and the display panel DPA. In
still another embodiment, the compensation film 152 may be
configured between the polarizer P and the reflective polarizer
120. In any of the aforementioned embodiments, the viewing angle
switchable device 100 may be replaced by the viewing angle
switchable device 200 of FIG. 2, the viewing angle switchable
device 300 of FIG. 3, the viewing angle switchable device 400 of
FIG. 4A or the viewing angle switchable device 500 of FIG. 5.
[0061] FIG. 10A and FIG. 10B are cross-sectional views respectively
in the X-Z reference plane and the Y-Z reference plane
schematically illustrating a viewing angle switchable display
module in the general display mode according to a fourth embodiment
of the invention. FIG. 10A and FIG. 10B respectively illustrate
travelling paths of environmental light beams with respect to the
X-Z reference plane and the Y-Z reference plane. FIG. 10C is a
cross-sectional view of the viewing angle switchable display module
in the peep-avoiding mode in the Y-Z reference plane according to
the fourth embodiment of the invention, and FIG. 10C illustrates
travelling paths of environmental light beams on the Y-Z reference
plane.
[0062] Referring to FIG. 10A, main differences between the viewing
angle switchable display module 40 of the fourth embodiment of the
invention and the viewing angle switchable display module 10 of
FIG. 6A are as follows. In the viewing angle switchable display
module 40, the display panel DP in FIG. 6A is replaced by an
organic light-emitting display panel DPB, and the viewing angle
switchable device 100 is disposed on a display surface SA of the
organic light-emitting display panel DPB. Moreover, the viewing
angle switchable display module 40 further includes a quarter wave
plate 170 disposed between the organic light-emitting display panel
DPB and the viewing angle switchable device 100.
[0063] For example, the organic light-emitting display panel DPB
includes a substrate SUB3, a conductive layer TC3, a light emitting
layer EL, and a metal layer ME, though the invention is not limited
thereto. The conductive layer TC3, the light emitting layer EL, and
the metal layer ME are sequentially disposed on the substrate SUB3
along the opposite direction of the direction Z. The substrate SUB3
is a transparent substrate to allow light beams (e.g. display light
beams) to pass through. The conductive layer TC3 is a transparent
conductive layer to allow light beams (e.g. the display light
beams) to pass through. The light emitting layer EL is adapted to
emit the display light beams when there is a potential difference
between the conductive layer TC3 and the metal layer ME. The metal
layer ME is adapted to reflect light beams (e.g. the display light
beams) transmitted thereto.
[0064] Referring to FIG. 10A and FIG. 10B, when there is no
potential difference between the transparent conductive layer TC1
and the transparent conductive layer TC2, travelling paths of the
display light beams (not shown) emitted by the light emitting layer
EL are similar to the travelling paths of the display light beams
B1 and B2 shown in FIG. 6A and FIG. 6B, thus details thereof are
not repeated. Moreover, when environmental light beams (e.g.
environmental light beams B5 and B6) are incident to the viewing
angle switchable device 100, both the environmental light beam B5
vertically entering the viewing angle switchable device 100 and the
environmental light beam B6 entering the viewing angle switchable
device 100 by a large angle are reflected by the metal layer ME and
then are blocked by the reflective polarizer 120. As a result, in
the general display mode, the display image is prevented from being
interfered by the environmental light beams.
[0065] Referring to FIG. 10C, when there is a potential difference
between the transparent conductive layer TC1 and the transparent
conductive layer TC2, each of the liquid crystal molecules LCM is
tilted due to an electric field. In FIG. 10C, the orthogonal
projection POA of the optical axis of each of the liquid crystal
molecules LCM on the absorptive polarizer 110 extends in the first
direction X, i.e. when there is a potential difference between the
transparent conductive layer TC1 and the transparent conductive
layer TC2, the orthogonal projection POA of the optical axis of
each of the liquid crystal molecules LCM on the absorptive
polarizer 110 is parallel to the transmission axis T110 of the
absorptive polarizer 110 and the transmission axis T120 of the
reflective polarizer 120, though the invention is not limited
thereto. In another embodiment, the orthogonal projection POA of
the optical axis of each of the liquid crystal molecules LCM on the
absorptive polarizer 110 may extend in a second direction Y, i.e.
when there is a potential difference between the transparent
conductive layer TC1 and the transparent conductive layer TC2, the
orthogonal projection POA of the optical axis of each of the liquid
crystal molecules LCM on the absorptive polarizer 110 may be
perpendicular to the transmission axis T110 of the absorptive
polarizer 110 and the transmission axis T120 of the reflective
polarizer 120.
[0066] Referring to FIG. 10C, when there is a potential difference
between the transparent conductive layer TC1 and the transparent
conductive layer TC2, travelling paths of the display light beams
(not shown) emitted by the light emitting layer EL are similar to
the travelling paths of the display light beams B1 and B2 shown in
FIG. 7A and FIG. 7B, thus details thereof are not repeated. It
should be noted that, in the peep-avoiding mode, for the
environmental light beams B5 and B6 on the Y-Z reference plane, a
polarization direction of the environmental light beam B5
vertically entering the viewing angle switchable device 100 is
parallel to the orthogonal projection POA of the optical axis of
each of the liquid crystal molecules LCM on the polarization plane,
so that the environmental light beam B5 vertically entering the
viewing angle switchable device 100 is reflected by the metal layer
ME and then is blocked by the reflective polarizer 120. On the
other hand, a polarization direction of an environmental light beam
B6 incident to the viewing angle switchable device 100 by a large
angle and the orthogonal projection POA of the optical axis of each
of the liquid crystal molecules LCM on the polarization plane form
an angle therebetween, such that the polarization direction of the
environmental light beam B6 is changed. Subsequently, a part of the
environmental light beam B6 is reflected by the reflective
polarizer 120. The environmental light beam B6 reflected by the
reflective polarizer 120 may again pass through the liquid crystal
layer LC to change the polarization direction of the environmental
light beam B6. Then, the environmental light beam B6 may pass
through the absorptive polarizer 110. Since the environmental light
beam B6 is reflected by the reflective polarizer 120 and then
passes through the absorptive polarizer 110, reflection of the
environmental light beam by the viewing angle switchable device 100
is enhanced. By enhancing the reflection of the environmental light
beam, the contrast of the large angle light leakage is decreased,
and thus a peep is further avoided.
[0067] In another embodiment, referring to the viewing angle
switchable display module 40A in FIG. 10D, to further avoid the
peep, another electrically controlled viewing angle switching
element 130 and an absorptive polarizer 110A may be disposed
between the reflective polarizer 120 and the quarter wave plate
170, wherein a transmission axis T110A of the absorptive polarizer
110A is parallel to the transmission axis T110 of the absorptive
polarizer 110 and the transmission axis T120 of the reflective
polarizer 120.
[0068] In another embodiment, referring to the viewing angle
switchable display module 40B in FIG. 10E, to further avoid the
peep, an additional absorptive polarizer 110A may be disposed
between the reflective polarizer 120 and the quarter wave plate 170
because generally the polarization rate of the absorptive polarizer
is better than the reflective polarizer.
[0069] In another embodiment, the viewing angle switchable device
100 of the viewing angle switchable display module 40 may be
replaced by the viewing angle switchable device 200 of FIG. 2, the
viewing angle switchable device 300 of FIG. 3, the viewing angle
switchable device 400 of FIG. 4A, or the viewing angle switchable
device 500 of FIG. 5. In still another embodiment, the viewing
angle switchable display module 40 may adopt the viewing angle
switchable device 100 of FIG. 1 (or the viewing angle switchable
device 200 of FIG. 2, the viewing angle switchable device 400 of
FIG. 4A, or the viewing angle switchable device 500 of FIG. 5), and
the viewing angle switchable display module 40 may further include
the compensation element 150 of FIG. 3, wherein the compensation
element 150, the organic light-emitting display panel DPB, and the
viewing angle switchable device 100 are overlapped with each other.
For example, the compensation element 150 and the viewing angle
switchable device 100 may be sequentially disposed on the organic
light-emitting display panel DPB, or positions of the compensation
element 150 and the viewing angle switchable device 100 may be
exchanged. The following embodiments can be improved as described
in this paragraph, and will not be repeated hereinafter.
[0070] FIG. 11 to FIG. 18 are cross-sectional views schematically
illustrating viewing angle switchable display modules according to
a fifth embodiment to a twelfth embodiment of the invention.
[0071] Referring to FIG. 11, main differences between the viewing
angle switchable display module 50 of the fifth embodiment of the
invention and the viewing angle switchable display module 40 of
FIG. 10A are as follows. The viewing angle switchable display
module 50 further includes a viewing angle reduction optical film
(e.g. a polarized type viewing angle control element 180) to
further improve the peep-avoiding effect. The viewing angle
reduction optical film may be a louver film, such as an advanced
light control film (ALCF). Alternatively, the viewing angle
reduction optical film may be the polarized type viewing angle
control element 180 shown in FIG. 11. In the embodiment, the
polarized type viewing angle control element 180 is located between
the viewing angle switchable device 100 and the quarter wave plate
170. In another embodiment, the viewing angle switchable device 100
may be located between the polarized type viewing angle control
element 180 and the quarter wave plate 170.
[0072] In the embodiment, the polarized type viewing angle control
element 180 includes a biaxial compensation film 181 and a
polarizer 182, wherein the biaxial compensation film 181 is located
between the polarizer 182 and the viewing angle switchable device
100. Specifically, when the polarized type viewing angle control
element 180 is located between the viewing angle switchable device
100 and the quarter wave plate 170, the biaxial compensation film
181 is located between the polarizer 182 and the reflective
polarizer 120 of the viewing angle switchable device 100.
[0073] Refractive indices of three principal axes of the biaxial
compensation film 181 include Nx, Ny, and Nz, wherein Nz is
parallel to a thickness direction of the biaxial compensation film
181, and every two of Nx, Ny, and Nz are perpendicular to each
other. In addition, an angle between Nx and any one of the
transmission axis T110 of the absorptive polarizer 110, the
transmission axis T120 of the reflective polarizer 120, and a
transmission axis T182 of the polarizer 182 is 45 degrees, and an
angle between Ny and any one of the transmission axis T110 of the
absorptive polarizer 110, the transmission axis T120 of the
reflective polarizer 120, and the transmission axis T182 of the
polarizer 182 is 45 degrees. If Nx>Nz, the transmission axis
T182 of the polarizer 182 is perpendicular to the transmission axis
T110 of the absorptive polarizer 110 and the transmission axis T120
of the reflective polarizer 120. By contrast, if Nz>Nx, the
transmission axis T182 of the polarizer 182 is parallel to the
transmission axis T110 of the absorptive polarizer 110 and the
transmission axis T120 of the reflective polarizer 120. In the
polarized type viewing angle control element 180, the biaxial
compensation film 181 provides an in-plane retardation within a
range from 200 nm to 300 nm, and the biaxial compensation film 181
provides an out-of-plane retardation within a range from 300 nm to
800 nm. The in-plane retardation of the biaxial compensation film
181 equals to (Nx-Ny)*D, wherein D represents the thickness of the
biaxial compensation film 181. The out-of-plane retardation of the
biaxial compensation film 181 equals to [(Nx+Ny)/2-Nz]*D.
[0074] In another embodiment, the viewing angle switchable device
100 may further include other layers according to needs. For
example, the viewing angle switchable device 100 may further
include at least one compensation film (not shown). When the
viewing angle switchable device 100 includes one compensation film,
the compensation film may be disposed between the electrically
controlled viewing angle switching element 130 and the reflective
polarizer 120 or between the electrically controlled viewing angle
switching element 130 and the absorptive polarizer 110. Besides,
the compensation film may be a C-type (e.g. negative C-type) plate,
an O-type plate, an A-type plate (preferably, two A-type plates), a
biaxial plate or a composite plate constructed by at least two of
the above four types of plates. On the other hand, when the viewing
angle switchable device 100 includes two or more compensation
films, the two or more compensation films may be disposed between
the electrically controlled viewing angle switching element 130 and
the reflective polarizer 120 and/or between the electrically
controlled viewing angle switching element 130 and the absorptive
polarizer 110. Besides, each of the compensation films may be a
C-type (e.g. negative C-type) plate, an O-type plate, an A-type
plate, a biaxial plate or a composite plate constructed by at least
two of the above four types of plates. The following embodiments
can be improved as described in this paragraph, and will not be
repeated hereinafter.
[0075] Referring to FIG. 12, main differences between the viewing
angle switchable display module 50A of the sixth embodiment of the
invention and the viewing angle switchable display module 50 of
FIG. 11 are as follows. In the viewing angle switchable display
module 50A, the viewing angle switchable device 100 is located
between the polarized type viewing angle control element 180 and
the quarter wave plate 170. Moreover, the biaxial compensation film
181 is located between the polarizer 182 and the absorptive
polarizer 110 of the viewing angle switchable device 100. The
following embodiments can be improved as described in this
paragraph (switch positions of the viewing angle switchable device
and the polarized type viewing angle control element), and will not
be repeated hereinafter.
[0076] Referring to FIG. 13, main differences between the viewing
angle switchable display module 50B of the seventh embodiment of
the invention and the viewing angle switchable display module 50 of
FIG. 11 are as follows. In the viewing angle switchable display
module 50B, the polarized type viewing angle control element 180B
includes not only the biaxial compensation film 181 and the
polarizer 182 but also a biaxial compensation film 183 and a
polarizer 184, wherein the biaxial compensation films and the
polarizers are alternately arranged. Specifically, when the
polarized type viewing angle control element 180B is located
between the viewing angle switchable device 100 and the quarter
wave plate 170, the biaxial compensation film 181, the polarizer
182, the biaxial compensation film 183 and the polarizer 184 are
sequentially disposed on a side of the viewing angle switchable
device 100 closer to the quarter wave plate 170. In another
embodiment, when the viewing angle switchable device 100 is located
between the polarized type viewing angle control element 180B and
the quarter wave plate 170, the biaxial compensation film 181, the
polarizer 182, the biaxial compensation film 183 and the polarizer
184 are sequentially disposed on a side of the viewing angle
switchable device 100 away from the quarter wave plate 170.
[0077] An angle between a transmission axis T184 of the polarizer
184 and Nx of the biaxial compensation film 183 is 45 degrees as
well. If Nx>Nz, the transmission axis T184 of the polarizer 184
and the transmission axis T182 of the polarizer 182 are
perpendicular to each other, and the transmission axis T184 of the
polarizer 184 and the transmission axis T120 of the reflective
polarizer 120 are parallel to each other. By contrast, if Nz>Nx,
the transmission axis T184 of the polarizer 184, the transmission
axis T182 of the polarizer 182, and the transmission axis T120 of
the reflective polarizer 120 are parallel to one another.
[0078] Referring to FIG. 14, main differences between the viewing
angle switchable display module 50C of the eighth embodiment of the
invention and the viewing angle switchable display module 50 of
FIG. 11 are as follows. In the viewing angle switchable display
module 50C, the polarized type viewing angle control element 180C
includes not only the biaxial compensation film 181 and the
polarizer 182 but also an A-plate 185, wherein the A-plate 185 is
disposed between the viewing angle switchable device 100 and the
polarizer 182 and overlaps the biaxial compensation film 181. For
instance, the A-plate 185 may be located between the biaxial
compensation film 181 and the polarizer 182 (as shown in FIG. 14),
or the biaxial compensation film 181 may be located between the
A-plate 185 and the polarizer 182. In addition, an optical axis I
of the A-plate 185 is parallel to Nx of the biaxial compensation
film 181. In the embodiment, the sum of the in-plane retardations
provided by the biaxial compensation film 181 and by the A-plate
185 falls within a range from 200 nm to 300 nm, and the sum of the
out-of-plane retardations provided by the biaxial compensation film
181 and by the A-plate 185 falls within a range from 300 nm to 800
nm.
[0079] In another embodiment, the A-plate 185 may be replaced by a
C-plate, the sum of in-plane retardations provided by the biaxial
compensation film and the C-plate falls within a range from 200 nm
to 300 nm, and the sum of out-of-plane retardations provided by the
biaxial compensation film and the C-plate falls within a range from
300 nm to 800 nm. In yet another embodiment, the A-plate 185 may be
replaced by the combination of the A-plate and the C-plate, the sum
of in-plane retardations provided by the biaxial compensation film
and the combination of the A-plate and the C-plate falls within a
range from 200 nm to 300 nm, and the sum of out-of-plane
retardations provided by the biaxial compensation film and the
combination of the A-plate and the C-plate falls within a range
from 300 nm to 800 nm.
[0080] Referring to FIG. 15, main differences between the viewing
angle switchable display module 50D of the ninth embodiment of the
invention and the viewing angle switchable display module 50 of
FIG. 11 are as follows. In the viewing angle switchable display
module 50D, the polarized type viewing angle control element 180D
includes not only the polarizer 182 but also a first O-plate
compensation film 186 having a first optical axis OA1 and a second
O-plate compensation film 187 overlapped with the first O-plate
compensation film 186 and having a second optical axis OA2. The
first O-plate compensation film 186 and the second O-plate
compensation film 187 are located between the polarizer 182 and the
viewing angle switchable device 100. In the embodiment, the second
O-plate compensation film 187 is located between the first O-plate
compensation film 186 and the polarizer 182. In another embodiment,
the first O-plate compensation film 186 may be located between the
second O-plate compensation film 187 and the polarizer 182.
[0081] A transmission axis T182 of the polarizer 182 is parallel to
the transmission axis T110 of the absorptive polarizer 110 and the
transmission axis T120 of the reflective polarizer 120, an
orthogonal projection OP1 of the first optical axis OA1 on the
polarizer 182 is parallel or perpendicular to the transmission axis
T182 of the polarizer 182. The second optical axis OA2 and the
first optical axis OA1 have opposite inclination directions, and an
orthogonal projection OP2 of the second optical axis OA2 on the
polarizer 182 is parallel or perpendicular to the transmission axis
T182 of the polarizer 182. Specifically, as shown in a dash line
frame X1, the transmission axis T110, the transmission axis T120,
and the transmission axis T182 may respectively extend in the first
direction X. In addition, the orthogonal projection OP1 of the
first optical axis OA1 on the polarizer 182 and the orthogonal
projection OP2 of the second optical axis OA2 on the polarizer 182
are parallel to the transmission axis T110, the transmission axis
T120, and the transmission axis T182. Alternatively, as shown in a
dash line frame X2, the transmission axis T110, the transmission
axis T120, and the transmission axis T182 may respectively extend
in the second direction Y. In addition, the orthogonal projection
OP1 of the first optical axis OA1 on the polarizer 182 and the
orthogonal projection OP2 of the second optical axis OA2 on the
polarizer 182 are perpendicular to the transmission axis T110, the
transmission axis T120, and the transmission axis T182.
[0082] As the orthogonal projection OP1 of the first optical axis
OA1 and the orthogonal projection OP2 of the second optical axis
OA2 are parallel to the first direction X, the polarized type
viewing angle control element 180D is able to limit the viewing
angle in the second direction Y. In another embodiment, the
orthogonal projection OP1 of the first optical axis OA1 and the
orthogonal projection OP2 of the second optical axis OA2 may be
parallel to the second direction Y. Accordingly, the polarized type
viewing angle control element 180D may limit the viewing angle in
the first direction X.
[0083] An acute angle included between the first optical axis OA1
and the polarizer 182 (i.e., an acute angle .theta.1 included
between the first optical axis OA1 and the orthogonal projection
OP1) is the same as or similar to an acute angle included between
the second optical axis OA2 and the polarizer 182 (i.e., an acute
angle .theta.2 included between the second optical axis OA2 and the
orthogonal projection OP2). The viewing angle of the polarized type
viewing angle control element 180D may become narrowed as the acute
angle becomes greater. Besides, as the acute angle becomes greater,
the polarized type viewing angle control element 180D gradually
shows light leakage at a large angle. As the acute angle becomes
smaller, the viewing angle of the polarized type viewing angle
control element 180D gradually becomes broader. Hence, by keeping
the acute angle within a range from 20.degree. to 50.degree., the
polarized type viewing angle control element 180D may have a
narrowed viewing angle and have less light leakage at a large
angle. Specifically, in the embodiment, the acute angle included
between the first optical axis OA1 and the polarizer 182 (i.e., the
acute angle .theta.1 included between the first optical axis OA1
and the orthogonal projection OP1) falls within the range from
20.degree. to 50.degree., and the acute angle included between the
second optical axis OA2 and the polarizer 182 (i.e., the acute
angle .theta.2 included between the second optical axis OA2 and the
orthogonal projection OP2) falls within the range from 20.degree.
to 50.degree.. In addition, a difference between the acute angle
.theta.1 and the acute angle .theta.2 is no more than 5
degrees.
[0084] In addition, the viewing angle of the polarized type viewing
angle control element 180D may be narrowed as the phase retardation
value of the O-plate compensation film increases. Besides, as the
phase retardation value of the O-plate compensation film increases,
the polarized type viewing angle control element 180D gradually
shows some light leakage at a large angle. As the phase retardation
value of the O-plate compensation film decreases, the viewing angle
of the polarized type viewing angle control element 180D gradually
becomes broader. Hence, by keeping the phase retardation value
within a range from 100 nm to 400 nm, the polarized type viewing
angle control element 180D may have a narrowed viewing angle and
have no light leakage at a large angle. Specifically, in the
embodiment, the phase retardation value of the first O-plate
compensation film 186 falls within the range from 100 nm to 400 nm,
and the phase retardation value of the second O-plate compensation
187 falls within the range from 100 nm to 400 nm. In addition, a
difference between the phase retardation value of the first O-plate
compensation film 186 and the phase retardation value of the second
O-plate compensation film 187 is no more than 50 nm.
[0085] In another embodiment, the polarized type viewing angle
control element 180D may further include other layers according to
needs. For example, the polarized type viewing angle control
element 180D may further include an adhesive layer (not shown). The
adhesive layer (e.g. an optical clear adhesive) is located between
the first O-plate compensation film 186 and the second O-plate
compensation film 187. In yet another embodiment, the polarized
type viewing angle control element 180D may further include another
polarizer having a transmission axis parallel to the transmission
axis T182 of the polarizer 182. The another polarizer may be
disposed adjacent to the polarizer 182 (e.g. the another polarizer
may be located between the second O-plate compensation film 187 and
the polarizer 182) to improve the light filtering effect at the
side where the polarizer 182 is located. The following embodiments
can be improved as described in this paragraph, and will not be
repeated hereinafter.
[0086] Referring to FIG. 16, main differences between the viewing
angle switchable display module 50E of the tenth embodiment of the
invention and the viewing angle switchable display module 50D of
FIG. 15 are as follows. In the viewing angle switchable display
module 50E, the viewing angle switchable device 100 is located
between the polarized type viewing angle control element 180D and
the quarter wave plate 170. In the embodiment, the second O-plate
compensation film 187 is located between the first O-plate
compensation film 186 and the polarizer 182. In another embodiment,
the first O-plate compensation film 186 may be located between the
second O-plate compensation film 187 and the polarizer 182. The
following embodiments can be improved as described in this
paragraph (switch positions of the viewing angle switchable device
and the polarized type viewing angle control element and/or switch
positions of the first O-plate compensation film and the second
O-plate compensation film), and will not be repeated
hereinafter.
[0087] Referring to FIG. 17, main differences between the viewing
angle switchable display module 50F of the eleventh embodiment of
the invention and the viewing angle switchable display module 50D
of FIG. 15 are as follows. In the viewing angle switchable display
module 50F, the polarized type viewing angle control element 180F
includes not only the first O-plate compensation film 186, the
second O-plate compensation film 187, and the polarizer 182 but
also a compensation film 188. The compensation film 188 may be
located between the first O-plate compensation film 186 and the
second O-plate compensation film 187, between the first O-plate
compensation film 186 and the polarizer 182, or between the second
O-plate compensation film 187 and the polarizer 182. In the
embodiment, the compensation film 188 is located between the first
O-plate compensation film 186 and the second O-plate compensation
film 187.
[0088] The compensation film 188 may be a C-plate compensation film
or an O-plate compensation film. Taking the compensation film 188
as a C-plate compensation film as an example, the optical axis OA
of the compensation film C is parallel to a thickness direction of
the polarized type viewing angle control element 180F (the
direction Z). The compensation film 188 may serve to modify a light
filtering range and the transmittance. For example, the
compensation film 188 may offer an out-of-plane retardation of 150
nm, so as to further facilitate the anti-peep effect. It should be
noted that, while FIG. 17 only illustrates one compensation film
188, the number of the compensation film 188 may be modified based
on needs, and is not limited to the illustration of FIG. 17. The
modification is applicable to all the following embodiments.
Therefore, details in this regard will not be repeated in the
following.
[0089] Referring to FIG. 18, main differences between the viewing
angle switchable display module 50G of the twelfth embodiment of
the invention and the viewing angle switchable display module 50D
of FIG. 15 are as follows. In the viewing angle switchable display
module 50G, the polarized type viewing angle control element 180G
includes not only the first O-plate compensation film 186, the
second O-plate compensation film 187, and the polarizer 182 but
also two compensation films 188. The compensation films 188 are
respectively located between the polarized type viewing angle
control device 100 and the first O-plate compensation film 186 and
between the second O-plate compensation film 187 and the polarizer
182. The two compensation films 188 may be C-plate compensation
films or O-plate compensation films. Besides, the number of the
compensation films 188 may be modified based on needs, and is not
limited to the illustration of FIG. 18. The modification is
applicable to all the following embodiments. Therefore, details in
this regard will not be repeated in the following.
[0090] In summary, the embodiments of the invention have at least
one of the following advantages or effects. In the embodiments of
the invention, an inclination direction of the liquid crystal
molecules in the viewing angle switchable device is controlled by
changing a potential difference between the two transparent
conductive layers. A phase delay is caused in the light beam
entering the viewing angle switchable device by a large angle, and
this light beam thus cannot pass through the absorptive polarizer.
Therefore, the range of the viewing angle is narrowed and a peep is
substantially avoided. Moreover, by configuring at least one
compensation film, the viewing angle switchable device may mitigate
the large angle light leakage and enlarge a peep-avoiding range on
azimuth. Furthermore, by configuring the reflective polarizer, the
environmental light beam entering the viewing angle switchable
device by a large angle is reflected by the reflective polarizer to
enhance the reflection of the environmental light beam by the
viewing angle switchable device. By enhancing the reflection of the
environmental light beam, a contrast of large angle light leakage
is decreased, so as to help avoid a peep from a large angle. A
plurality of openings may be formed on the reflective polarizer to
block the large angle light leakage, so as to further improve the
peep-avoiding effect. The viewing angle switchable display module
employing the viewing angle switchable device may be switched
between the general display mode and the peep-avoiding mode in an
electric control manner, and a backlight module may be optionally
selected for the non-self-luminous display panel used with the
viewing angle switchable display module. By disposing a quarter
wave plate between an organic light-emitting display panel and a
viewing angle switchable device, the display image is prevented
from being interfered by the environmental light beam. Also, the
contrast of the large angle light leakage is decreased in the
peep-avoiding mode, and thus a peep is further avoided. In some
embodiments, a viewing angle reduction optical film (e.g. a louver
film or a polarized type viewing angle control element) may be
further disposed to overlap with the viewing angle switchable
device so as to further improve the peep-avoiding effect.
[0091] The foregoing description of the preferred embodiments of
the invention has been presented for purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise form or to exemplary embodiments
disclosed. Accordingly, the foregoing description should be
regarded as illustrative rather than restrictive. Obviously, many
modifications and variations will be apparent to practitioners
skilled in this art. The embodiments are chosen and described in
order to best explain the principles of the invention and its best
mode practical application, thereby to enable persons skilled in
the art to understand the invention for various embodiments and
with various modifications as are suited to the particular use or
implementation contemplated. It is intended that the scope of the
invention be defined by the claims appended hereto and their
equivalents in which all terms are meant in their broadest
reasonable sense unless otherwise indicated. Therefore, the term
"the invention", "the present invention" or the like does not
necessarily limit the claim scope to a specific embodiment, and the
reference to particularly preferred exemplary embodiments of the
invention does not imply a limitation on the invention, and no such
limitation is to be inferred. The invention is limited only by the
spirit and scope of the appended claims. Moreover, these claims may
refer to use "first", "second", etc. following with noun or
element. Such terms should be understood as a nomenclature and
should not be construed as giving the limitation on the number of
the elements modified by such nomenclature unless specific number
has been given. The abstract of the disclosure is provided to
comply with the rules requiring an abstract, which will allow a
searcher to quickly ascertain the subject matter of the technical
disclosure of any patent issued from this disclosure. It is
submitted with the understanding that it will not be used to
interpret or limit the scope or meaning of the claims. Any
advantages and benefits described may not apply to all embodiments
of the invention. It should be appreciated that variations may be
made in the embodiments described by persons skilled in the art
without departing from the scope of the present invention as
defined by the following claims. Moreover, no element and component
in the present disclosure is intended to be dedicated to the public
regardless of whether the element or component is explicitly
recited in the following claims.
* * * * *